Severe coronary stenosis with no evidence of plaques

|14/12/2020

Mohamed Marwan, MD
Department of Radiology, University Hospital Erlangen, Erlangen, Germany

A 56-year-old female patient, complaining of exertional dyspnea, was referred for an outpatient coronary CT angiography. Her medical history was unremarkable, apart from a positive treadmill stress ECG test. She had neither known risk factors, nor family history of coronary artery disease (CAD). A coronary CT angiography (cCTA) was performed for evaluation.

cCTA images revealed a severe stenosis at the ostium of the left circumflex artery (LCX) with no evidence of any atherosclerotic plaque. No stenoses were found in the rest of the coronary arteries and their branches. The patient underwent invasive coronary angiography (ICA), which confirmed the diagnosis. However, due to the difficult anatomy which was not suitable for interventional treatment, the patient was referred for bypass surgery.

MPR, MIP and cVRT images show a severe stenosis at proximal LCX, without any evidence of plaque.

Courtesy of Department of Radiology, University Hospital Erlangen, Erlangen, Germany

Fig. 1:

MPR (Fig. 1a), MIP (Fig. 1b) and cVRT (Figs. 1c and 1d) images show a severe stenosis (arrows) at proximal LCX, without any evidence of plaque.

cCTA is an established non-invasive imaging modality that provides robust assessment of CAD, owing to the continuous evolution of CT technologies, especially since the introduction of dual source CT (DSCT). This technology uses two X-ray tubes and two detectors arranged at 90° angles, allowing reconstruction of cross-sectional images at one quarter of the gantry rotation time, thus significantly improving the temporal resolution. This case was acquired with the very first dual source CT scanner clinically available – SOMATOM Definition. A severe stenosis at the ostium of the LCX was clearly depicted and freely demonstrated in three dimensions. While in ICA, it could have been challenging to project this lesion and potentially miss it especially if prior knowledge from CT was not available. Coronary stenosis is normally associated with the presence of plaques – either calcified or non-calcified. Coronary stenosis without evidence of plaques, such as this case, is rarely seen. The underlying cause of such a stenosis is unknown and yet to be investigated.

Angiographic images show a severe stenosis at the ostium of the LCX, which is challenging to project and could potentially be missed without the prior knowledge from CT.

Courtesy of Department of Radiology, University Hospital Erlangen, Erlangen, Germany

Fig. 2:

Angiographic images show a severe stenosis (arrows) at the ostium of the LCX, which is challenging to project and could potentially be missed without the prior knowledge from CT.

Scanner

Scan area

Heart

Scan mode

Retrospective ECG-gated spiral scan

Scan length

123.3 mm

Scan direction

Crandio-caudal

Scan time

10.3 s

Tube voltage

120 kV

Effective mAs

157 mAs

Dose modulation

CARE Dose4D

CTDIvol

41.3 mGy

DLP

508 mGy cm

Rotation time

0.33 s

Pitch

0.22

Slice collimation

64 x 0.6 mm

Slice width

0.6 mm

Reconstruction increment

0.3 mm

Reconstruction kernel

B26f

Heart rate

51 - 54 bpm

Contrast

350 mg/mL

Volume

60 mL + 50 mL saline

Flow rate

6 mL/s

Start delay

Test Bolus